1. Field of the Invention
The present invention relates to a centering and drilling method and machine, in which the drill bit and the component to be bored rotate in opposite directions. The present invention allows an exact concentric passage to be drilled that has greater accuracy than prior art techniques.
2. Background Art
With prior art devices, the drilled bore is not perfectly concentric, particularly for longer components. A minute offset or angle existing between the centerline of the drill and the centerline of the component at the starting position will result in the center of the passage not being co-linear with the centerline of the component along the length thereof. Such variation or offset in the position of the passage is undesired, particularly in components requiring exacting tolerances.
Prior art methods traditionally encompass a system in which the component is stationarily positioned and the drill bit rotates. The rotating drill bit is then moved toward and longitudinally through the component to bore a passage therein. Since minute offsets between the axis of the drill bit and the longitudinal axis of the component cause the passage to be non-concentric, many attempts have been made in the prior art to overcome this problem. One approach is using guides for the drill or component, which is disclosed for example in U.S. Pat. Nos. 3,371,560 to Kaser, 4,470,116 to Wellach, and 1,376,791 to Baker et al. Furthermore, U.S. Pat. Nos. 3,674,375, 2,330,577, 800,599, 1,529,557, 787,893, and 766,748 relate generally to work holders and centering devices.
U.S. Pat. No. Re 24,289 to Farnsworth discloses a different drilling device, in which the component is rotated about its longitudinal axis and the drill bit is stationary. However, these disclosed prior art techniques fail to bore a perfectly concentric passage in the component consistently, particularly for longer components. A problem is that the operator's ability to align exactly the axis of the drill bit with the longitudinal axis of the component is limited.
Therefore, a need exists in the art for a system that consistently allows concentric passages to be bored through a component. The system should be self-correcting so that a very slight misalignment by the operator is continually corrected as the system bores the passage. It is also desired that the system be inexpensive and easy to use.